The present invention relates to a semiconductor device, and more particularly, to a semiconductor device having a vertical transistor which can eliminate a floating body effect and a method for manufacturing the same.
Recently, in the semiconductor industry, technologies have been developed to increase the degree of integration, the operational speed and the functionality of a semiconductor device. For example, in order to overcome limitations in the degree of integration and the current of a semiconductor device having an existing planar transistor, a semiconductor device having a vertical transistor has been developed.
Unlike the existing planar transistor in which source and drain regions are formed on opposite sides of a substrate so that a channel region is formed in a horizontal direction, the vertical transistor includes source and drain regions that are formed above and below a substrate so that a channel region is formed in a vertical direction. In the vertical transistor, due to the vertical channel region, high integration is possible. Since a channel length can be increased even with the high integration, the short channel effect can be suppressed.
However, in the conventional vertical transistor, it is difficult to form a DRAM cell structure by itself. Also, since the body of the transistor is floated from the substrate, the floating body effect is induced by reverse bias between a source region and the substrate. Therefore, in a semiconductor device having the conventional vertical transistor, it is difficult to adjust the characteristics of the semiconductor device.